For many years the deployment of telecommunication systems, for different standards and many frequency bands, has been realized to a large extent by placing radio base stations (RBS) in cellular networks covering large areas. An important link in a traditional radio base station architecture is between the active parts of the system (that is the digital and analog components of the system) to the passive parts (such as the filters and antennas). This high-power analog radio-frequency (RF) link is critical in the sense that it sometimes requires long cables of high quality and large dimensions, in order keep the unavoidable signal quality losses and power losses to a minimum. Such links suffer from the disadvantage of having high costs.
There has been a recent change to integrate the power amplifier and other RF blocks more closely with the physical antenna in order to avoid this critical link, and has resulted in what is termed an integrated antenna unit (IAU). In order to implement a base station today with two or more frequency bands, several complete receivers are combined on the analogue side after a receiver filter.
Thus, when implementing receivers for multiple frequency bands, two or more receivers are implemented in the analogue domain, one receiver for each frequency band. FIG. 1 shows such a receiver having multiple analogue receivers, each analogue receiver adapted to convert a respective radio frequency band into base band, for subsequent analogue to digital processing.
This type of technology has a disadvantage in that the multi band receivers become bulky, and have low energy efficiency and increased manufacturing cost due to the fact that several complete RF receivers in the analogue domain are used to implement the multi band receivers.